time complexity

Question

Comments

Means you are merging into another temporary array. Right ?

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yes as usual like merge sort do

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Ok ok... got it.

Answer 1

1.Sort one of the array. This can be done in O(nlogn).

2.Each value of unsorted array treat as key for sorted array and run binary search on sorted array for each element of unsorted array. If there is element found in sorted array. Simply store any flag like INT_MAX value to skip later at the time of printing values containing (A-B).And this can also done in O(nlogn).
 

3. Print all values of sorted array except flag value.

If this was programming question. I would go with this approach to write code. :P

Comments

and one on the sorted array A   2   4   7    14

suppose unsorted array B         4   1     5    4   9

as u said choosing 4 as key in unsorted array B and applying binary search on sorted array A, match found placing a flag to both now take key 1 fine next key 5 fine, now again 4 what will u do, how  u will differentiate 1 falg with other flag

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Why we need to differentiate flags?
when we find key in sorted array then we place INT_MAX (Defines maximum value in integer) act as flag.
In above your example, once 4 is found in sorted array then we remove it from sorted array by placing flag. If there is again 4 come in unsorted array, we'll not have match in sorted array. In fact we ignore it and go for search for another element. However, there will distinct values in both array then this condition will not arise.
At last we have sorted array not having elements which belong to unsorted array instead of there is flag value.